Signal rockets or flares are pyrotechnic devices which are well known articles of commerce. They are used on a large scale for signalling and terrain illumination. The signals are available with red, white, and green illuminants or with red, green, or yellow smoke. J.H. McLain, in "Pyrotechnics", The Franklin Institute Press, Philadelphia, Pa., 1980, pages 109 and 110 describes the M127A1 and related M125A1 and M126A1 hand held signal rockets. McLain also describes the weight, size, shape, and composition of the black powder propulsion pellet. A composition of 91% black powder, 9% calcium carbonate and a moisture content of 1.8-2.5% is described by McLain. The M127A1 signal rocket is fired by hand from an expendable launcher.
Signal rockets have been powered with black powder charges. A problem of black powder is its variable burning behavior from batch to batch. This variability originates from inconsistencies in the quality of charcoal which makes up ten percent of the black powder weight. As a result of this variability many black powder plants blew up so that, currently, there is only one domestic black powder plant. Thus, black powder's safety problem created also a single-source problem.
Accordingly, a need exists for a more reliable process and for substitute products which have approximately the same percentages of potassium nitrate and sulfur as black powder.
In my copending patent application Ser. No. 094,411, filed Jul. 8, 1993, which is herewith incorporated by reference, methods and compositions are described for articles and products that are made from charcoal-free black powder type granules that, in closed bomb tests, have a burn rate and pressure development rate comparable to that of standard black powder. The products are dispersions of unconverted phenolphthalein, potassium nitrate and sulfur in a binding phase of phenolphthalein salt. The products have a characteristic red color which is indicative of the presence of the phenolphthalein salt. For clarity in this specification, the energetic compositions of the earlier application will be hereinafter collectively referred to as "red powder".
Among the various pyrotechnic devices, the M127A1 signal rocket is an important technical demonstration because of the required cooperation of elements that is necessary to effect sequential burning of the initiating, expelling, delay and propelling charges of the signal rocket. This signal rocket has a minimal elevation of 650 feet,
The benefits of the substitution of red powder granules and consolidated red powder in conventional articles which have used black powder are set forth in detail below.